First of all, when the customer enters the shop (he's referred to in the scripts as "Mousebender"), there's no extended "good morning" exchange. The shopkeeper just says "Good Morning!" as the first line in the sketch, and Mousebender launches into his "sitting in the public library" line.

Secondly, in the original skit it's just music, not bazouki playing. In what may be one of the funniest parts of the skit that isn't mentioned here, after Mousebender says "I like a nice dance, you're forced to!", there's a quick cut to a Viking who says "Anyway..." Cut back to the shopkeeper who looks around in alarm and yells "Who said that?!"

Now, for the coolest part of the skit, I'll just reproduce the original lines since this writeup differs rather greatly, starting at "It was an act of pure optimism to pose the question in the first place."

Mousebender (John Cleese): Tell me something, do you have any cheese at all?

Wensleydale (Michael Palin): Yes, sir.

MB: Now I'm going to ask you that question once more, and if you say 'no' I'm going to shoot you through the head. Now, do you have any cheese at all?

WD: No.

MB: (shoots him) What a senseless waste of human life.

Mousebender puts a cowboy hat on his head. Cut to stock shot of man on horse riding into the sunset. Music swells dramatically.

This is John Cleese's favorite sketch. The Monty Python cast was walking around one day, when one of them (I believe it was Graham Chapman) stated that he really felt like eating cheese. Someone said "Do you suppose that drugstore would have cheese?" This idea seemed so absurd that it led to a sketch in which a customer enters a drugstore asking for various types of cheese.

After some brainstorming, Cleese asked himself why someone would be asking for cheese in a drugstore. The logical conclusion? The cheese shop didn't have any!

According to Cleese, he was terribly worried while writing that the sketch wasn't going to be funny at all. Basically, it was a list of cheeses that he had written down while researching the sketch at a local cheese shop. He kept looking up to Chapman, who would puff his pipe and calmy state that what Cleese was writing was extremely funny.